By dynamically changing the volt-ampere characteristic

the controllable metal oxide arrester（MOA） can achieve the deep limitation of the switching overvoltage

and thus eliminate the closing resistor of circuit breaker in UHV system and improve the economy and reliability of UHV projects. We investigated the influences of controllable MOA on the amplitude

distribution and waveform characteristics of closing overvoltage

and also investigated the adaptability of parameters of the controllable MOA for different system conditions and line lengths. Moreover

we proposed a parameter configuration of the controllable MOA to eliminate the closing resistor of circuit breaker

analyzed the control strategy and implementation method of controllable MOA

and studied the working conditions of the controlled MOA with different parameters under different operating conditions. The research results show that

by using controllable MOA with controllable ratio of 15% to 25%

the closing overvoltage for UHV lines with length of less than 400 km can be limited within the allowable range. The control of the controllable MOA can be realized by monitoring the line voltage to determine the line status. Under the proposed parameter configuration and control strategy

the energy consumption and the power frequency voltage withstand of the controllable MOA can meet requirements.